i have a 2000 volvo s40, thumping sound coming form the front, think its the wheel bearing? have 160K miles ?

Make sure no one is hiding under the hood. If not, it is best to take it to the dealer.

Probably bad ball joints or bearings.

It is not best to take it to the dealer. The dealer over charges for every part that they sell.
Bad Wheel Bearings usually make a grinding noise rather than a thumping noise.
l suggest u take it to a local shop. l also suggest u buy wheel bearings online. You can get a very good deal at http://mibearings.com .
Go to their front page & fill out the form on the right. They will look-up bearings for u & email u with a price & link to purchase it.
l hope that helps!

Im about to buy a Volvo S40, so please do not put me off, there beautiful cars. but to answer your question if your cars 160k, then thumping is its way of telling you its on the way out, get it checked out at a garage.